1. Field of the Invention
The present invention relates to a light emitting diode (LED) package, and more particularly, a method of fabricating an LED package having enhanced adhesion strength between a resin-molded part and a package substrate.
2. Description of the Related Art
In general, a light emitting diode (LED) is adopted extensively, ranging from small electronic devices like mobile communication terminals to large-sized displays like traffic lights and automobile lamps. Such an LED requires a package that ensures high luminance while providing good protection against heat and is durable in all kinds of external environment.
In general, an LED package has a structure with an LED chip therein, sealed by a resin-molded part, which however is heterogeneous from a substrate such as made of silicon, and thus the interface therebetween is weak in adhesion strength, and they may easily be separated. FIG. 1 is a cross-sectional view illustrating a conventional white LED package.
Referring to FIG. 1, the LED package 10 includes a lower substrate 11 and an upper substrate 12 having a cavity formed therein. The lower substrate 11 has adequate metal patterns such as lead frames 14a and 14b, conductive vias 15a and 15b, and bonding pads 16a and 16b. An LED 18 is mounted in a mounting area defined by a cavity and can be electrically connected to the lead frames 14a and 14b via connecting means like wires. A resin-molded part 19 is formed in the mounting area with the LED 18 mounted therein. The resin-molded part 19 typically has functions of protecting the LED 18, and with a specific phosphor contained therein, of converting a wavelength.
In general, the resin-molded part 19 is mainly composed of silicone, epoxy, urethane resin or a compound thereof, whereas the package substrate can adopt different material such as silicone having high heat conductivity and good machinability. In this respect, the resin-molded part 19 and the package substrate 11 and 12 can be bonded inadequately at interface A. This inadequate adhesion may allow penetration of moisture, degrading the reliability of the device, and further can result in fatal defects such as the resin-molded part 19 being separated under the suddenly changing temperature.
Therefore, there have been required a new technology in the field which can improve adhesion strength between the resin-molded part and the package substrate in an LED package.